Sanchez said people who have seen either of the vehicles of interest or the persons of interest should call the homicide unit tip line at (510) 238-7950, which is anonymous.

Oakland police said one person of interest is described as a male of unknown race who was wearing a light blue baseball hat, a light blue shirt with a large light-colored horizontal stripe across the back and chest and dark colored pants.

Police described the second person of interest as a black woman who was wearing layers of clothing and a headscarf and the third person of interest as a thin person of unknown race and unknown gender.

There is a reward of up to $30,000 for information leading to the arrest of the person or persons responsible for killing Bole.

According a statement released by Bole's family after he was killed, Bole was born and raised in Tampa, Fla., and earned a degree in mathematics from Florida State University and a doctorate in electrical engineering from Georgia Tech.

His family said that while Bole was a student he had a NASA fellowship at Ames Research Center in Mountain View, specializing in fault analysis, which involved predicting and reducing the risk of system failures in unmanned aircraft.

But his family said Bole's "true passion was health care" and that in 2015 he was hired for his dream job as a data scientist at Armus Corp. in San Mateo, where he was still working at the time of his death.

Bole's family said he loved hiking and camping and "spent many hours exploring San Francisco and Oakland, especially their ethnic restaurants and craft brew pubs."

Bole's father, Brad Bole, said, "We were all proud of Brian's achievements, but we were more proud of the man he had become."